We may find difficulty in accepting Jesus' newest commandment; we allow our own selfishness to seep into our hearts, our own thoughts of how people and things should be hinder our ability to love as God does. So caught up in our desire for everything to go the way we want or the way we expect, we often don’t recognize our disobedience to God.
We analyze people's appearance, accent, culture and deem them as foreign to us. They don't belong, so naturally our needs come first. Maybe in your ideal vision, your son gets married and has children, but in reality, the person he falls in love with is not a women.
Or perhaps you spend a good deal of your life raising a boy only to find out that the whole time, you'd been raising a girl. You may be disappointed to discover that your child is more content to be a repairman than they are to be a lawyer. These might be ''bumps in the road'' as far as you're concerned but God's plan is coasting as He intended it to.
In God's Kingdom, there is no foreigner, no woman or man, no other classes to separate us. We are simply God's Children, who He Loves and will Love for eternity. Instead of concerning ourselves with 'perfecting' God’s creations, who He knows best, all we need to do is love them as we love God and as He loves us.